courierguy wrote:Once again the experimental aircraft are ahead of the curve, running an oil line through the firewall seems archaic to me, dangerous too The stubby little transducer on my Rotax uses no oil line, one less thing to worry about. It's interesting to me how the cert and exp camps can "compare notes" on what has worked for ever and is worth emulating, and what can be a new, better way to do things.

Thanks for the replies to what I thought might have been an uninformed question. So if I understand correctly, certified aircraft are required to keep an old system of routing an oil line to a Bourdon tube type panel mounted gauge, while experimental may use a much safer engine mounted electrical transducer and run the small electric signal to a dash mounted electric gauge?

On this same logic, I'm assuming older certified aircraft require the entire electrical system loads (charging and discharging) also be routed through the firewall to the panel mounted ammeter? This is also a safety issue since the current is so high, any compromise to the cable's insulation would result in a fire. My guess is on experimental a/c you could use a shunt between the battery and alternator and send the very small voltage difference across the know resistance value of the shunt to a panel mounted amp meter that is really just a voltmeter reading the voltage drop across the shunt and displaying that reading as amps.

deckofficer wrote:

courierguy wrote:Once again the experimental aircraft are ahead of the curve, running an oil line through the firewall seems archaic to me, dangerous too The stubby little transducer on my Rotax uses no oil line, one less thing to worry about. It's interesting to me how the cert and exp camps can "compare notes" on what has worked for ever and is worth emulating, and what can be a new, better way to do things.

Thanks for the replies to what I thought might have been an uninformed question. So if I understand correctly, certified aircraft are required to keep an old system of routing an oil line to a Bourdon tube type panel mounted gauge, while experimental may use a much safer engine mounted electrical transducer and run the small electric signal to a dash mounted electric gauge?

On this same logic, I'm assuming older certified aircraft require the entire electrical system loads (charging and discharging) also be routed through the firewall to the panel mounted ammeter? This is also a safety issue since the current is so high, any compromise to the cable's insulation would result in a fire. My guess is on experimental a/c you could use a shunt between the battery and alternator and send the very small voltage difference across the know resistance value of the shunt to a panel mounted amp meter that is really just a voltmeter reading the voltage drop across the shunt and displaying that reading as amps.

For what its worth, my Rotax engine was "certified". Or as certified as an SLSA has to be.....

Crzyivan13 wrote:

deckofficer wrote:

courierguy wrote:Once again the experimental aircraft are ahead of the curve, running an oil line through the firewall seems archaic to me, dangerous too The stubby little transducer on my Rotax uses no oil line, one less thing to worry about. It's interesting to me how the cert and exp camps can "compare notes" on what has worked for ever and is worth emulating, and what can be a new, better way to do things.

Thanks for the replies to what I thought might have been an uninformed question. So if I understand correctly, certified aircraft are required to keep an old system of routing an oil line to a Bourdon tube type panel mounted gauge, while experimental may use a much safer engine mounted electrical transducer and run the small electric signal to a dash mounted electric gauge?

On this same logic, I'm assuming older certified aircraft require the entire electrical system loads (charging and discharging) also be routed through the firewall to the panel mounted ammeter? This is also a safety issue since the current is so high, any compromise to the cable's insulation would result in a fire. My guess is on experimental a/c you could use a shunt between the battery and alternator and send the very small voltage difference across the know resistance value of the shunt to a panel mounted amp meter that is really just a voltmeter reading the voltage drop across the shunt and displaying that reading as amps.

For what its worth, my Rotax engine was "certified". Or as certified as an SLSA has to be.....

Certified allowing more modern technology such as oil pressure transducers and shunt derived amp meters.

deckofficer wrote:Now time for a dumb question from someone who is quite green when it comes to A&P. Is there a reason an oil pressure line is routed through the firewall instead of a pressure sensor that is engine mounted with wires going to an electric gauge?

Some of the old stuff (and new) was built with a non electrical system in mind so the mechanical oil pressure gauge was used. Most likely came from same tractor supply house as starters, and carbs therefore the same copper line was used also .

You may change this out for a transducer type in a certified aircraft with approved gauge. Or use flex hose as Mike recommends.
DENNY

N300RE wrote:I've had a cam go flat in flight, which pressured up the crankcase and blew the vacuum pump seal out causing all the oil to blow out the bottom. I shut the engine down before it lost pressure and was able to dead stick it to an airport. After the engine was replaced the stainless prop governor line cracked causing oil to cover the windshield, luckily it was clean oil and had to set it down in a field. Now it has a Teflon prop gov line.

I was talking oil pressure sensors with a friend and I brought this story up. Back when I wrote this I had yet to dig into my IO-540, which I now know intimately. Reading this comment, I'm curious how a cam goes flat in flight and how it can pressure the crankcase? What as the pathology there for such an outcome?

Lycoming or Continental?

Speaking of tractors:
I listened in on a couple of long gone pilots / mechanics telling about a flight from San Jose KRHV tell of a flight to Southern Calif. when they made a precautionary landing at Tulare Cailf. Analyzed the problem and went to the local farm equipment equivalent to NAPA Auto Parts and purchased a some Case tractor
[direct replacement] parts.

There are still two from that evening that alive who could back me up.

Wannabe right on:

The mechanical oil pressure gauge does not require electrical power, where as a pressure transducer and electric gauge do.

I think that is the main reason a lot of them remain. If you have an electrical failure, at least you have some working engine indications. Though, you would have to be pretty unlucky to have electrical problems and oil pressure issues at the same time..

A lot of certified aircraft have either one or the other, and from what I've seen the mechanical gauge is more reliable (or seems to be). And they do typically have flexible braided lines to the firewall, and hardlines from the firewall to the guage.
Most of the ones I've seen also have a pressure switch T'd inline that triggers an annunciator light on the panel to attract the pilots attention also.

The few hardlines I've seen usually have a coil wound into them between the firewall and engine to allow for movement and thermal expansion etc...